Design Studio Portal Page DME

Have you used the Checkbox on your Portal page DME to allow users to select records? A recent client asked me to design a portal page that would display PO agreements that are going to expire during the current month and allow users to select which ones to extend an additional month.

That was fairly easy to do until they asked me to include a button that would allow them to select all of the displayed records. After playing a bit, here's what I came up with.